// SPDX-License-Identifier: GPL-2.0
/*
* transport_class.c - implementation of generic transport classes
* using attribute_containers
*
* Copyright (c) 2005 - James Bottomley <[email protected]>
*
* The basic idea here is to allow any "device controller" (which
* would most often be a Host Bus Adapter to use the services of one
* or more tranport classes for performing transport specific
* services. Transport specific services are things that the generic
* command layer doesn't want to know about (speed settings, line
* condidtioning, etc), but which the user might be interested in.
* Thus, the HBA's use the routines exported by the transport classes
* to perform these functions. The transport classes export certain
* values to the user via sysfs using attribute containers.
*
* Note: because not every HBA will care about every transport
* attribute, there's a many to one relationship that goes like this:
*
* transport class<-----attribute container<----class device
*
* Usually the attribute container is per-HBA, but the design doesn't
* mandate that. Although most of the services will be specific to
* the actual external storage connection used by the HBA, the generic
* transport class is framed entirely in terms of generic devices to
* allow it to be used by any physical HBA in the system.
*/
#include <linux/export.h>
#include <linux/attribute_container.h>
#include <linux/transport_class.h>
static int transport_remove_classdev(struct attribute_container *cont,
struct device *dev,
struct device *classdev);
/**
* transport_class_register - register an initial transport class
*
* @tclass: a pointer to the transport class structure to be initialised
*
* The transport class contains an embedded class which is used to
* identify it. The caller should initialise this structure with
* zeros and then generic class must have been initialised with the
* actual transport class unique name. There's a macro
* DECLARE_TRANSPORT_CLASS() to do this (declared classes still must
* be registered).
*
* Returns 0 on success or error on failure.
*/
int transport_class_register(struct transport_class *tclass)
{
return class_register(&tclass->class);
}
EXPORT_SYMBOL_GPL(transport_class_register);
/**
* transport_class_unregister - unregister a previously registered class
*
* @tclass: The transport class to unregister
*
* Must be called prior to deallocating the memory for the transport
* class.
*/
void transport_class_unregister(struct transport_class *tclass)
{
class_unregister(&tclass->class);
}
EXPORT_SYMBOL_GPL(transport_class_unregister);
static int anon_transport_dummy_function(struct transport_container *tc,
struct device *dev,
struct device *cdev)
{
/* do nothing */
return 0;
}
/**
* anon_transport_class_register - register an anonymous class
*
* @atc: The anon transport class to register
*
* The anonymous transport class contains both a transport class and a
* container. The idea of an anonymous class is that it never
* actually has any device attributes associated with it (and thus
* saves on container storage). So it can only be used for triggering
* events. Use prezero and then use DECLARE_ANON_TRANSPORT_CLASS() to
* initialise the anon transport class storage.
*/
int anon_transport_class_register(struct anon_transport_class *atc)
{
int error;
atc->container.class = &atc->tclass.class;
attribute_container_set_no_classdevs(&atc->container);
error = attribute_container_register(&atc->container);
if (error)
return error;
atc->tclass.setup = anon_transport_dummy_function;
atc->tclass.remove = anon_transport_dummy_function;
return 0;
}
EXPORT_SYMBOL_GPL(anon_transport_class_register);
/**
* anon_transport_class_unregister - unregister an anon class
*
* @atc: Pointer to the anon transport class to unregister
*
* Must be called prior to deallocating the memory for the anon
* transport class.
*/
void anon_transport_class_unregister(struct anon_transport_class *atc)
{
if (unlikely(attribute_container_unregister(&atc->container)))
BUG();
}
EXPORT_SYMBOL_GPL(anon_transport_class_unregister);
static int transport_setup_classdev(struct attribute_container *cont,
struct device *dev,
struct device *classdev)
{
struct transport_class *tclass = class_to_transport_class(cont->class);
struct transport_container *tcont = attribute_container_to_transport_container(cont);
if (tclass->setup)
tclass->setup(tcont, dev, classdev);
return 0;
}
/**
* transport_setup_device - declare a new dev for transport class association but don't make it visible yet.
* @dev: the generic device representing the entity being added
*
* Usually, dev represents some component in the HBA system (either
* the HBA itself or a device remote across the HBA bus). This
* routine is simply a trigger point to see if any set of transport
* classes wishes to associate with the added device. This allocates
* storage for the class device and initialises it, but does not yet
* add it to the system or add attributes to it (you do this with
* transport_add_device). If you have no need for a separate setup
* and add operations, use transport_register_device (see
* transport_class.h).
*/
void transport_setup_device(struct device *dev)
{
attribute_container_add_device(dev, transport_setup_classdev);
}
EXPORT_SYMBOL_GPL(transport_setup_device);
static int transport_add_class_device(struct attribute_container *cont,
struct device *dev,
struct device *classdev)
{
struct transport_class *tclass = class_to_transport_class(cont->class);
int error = attribute_container_add_class_device(classdev);
struct transport_container *tcont =
attribute_container_to_transport_container(cont);
if (error)
goto err_remove;
if (tcont->statistics) {
error = sysfs_create_group(&classdev->kobj, tcont->statistics);
if (error)
goto err_del;
}
return 0;
err_del:
attribute_container_class_device_del(classdev);
err_remove:
if (tclass->remove)
tclass->remove(tcont, dev, classdev);
return error;
}
/**
* transport_add_device - declare a new dev for transport class association
*
* @dev: the generic device representing the entity being added
*
* Usually, dev represents some component in the HBA system (either
* the HBA itself or a device remote across the HBA bus). This
* routine is simply a trigger point used to add the device to the
* system and register attributes for it.
*/
int transport_add_device(struct device *dev)
{
return attribute_container_device_trigger_safe(dev,
transport_add_class_device,
transport_remove_classdev);
}
EXPORT_SYMBOL_GPL(transport_add_device);
static int transport_configure(struct attribute_container *cont,
struct device *dev,
struct device *cdev)
{
struct transport_class *tclass = class_to_transport_class(cont->class);
struct transport_container *tcont = attribute_container_to_transport_container(cont);
if (tclass->configure)
tclass->configure(tcont, dev, cdev);
return 0;
}
/**
* transport_configure_device - configure an already set up device
*
* @dev: generic device representing device to be configured
*
* The idea of configure is simply to provide a point within the setup
* process to allow the transport class to extract information from a
* device after it has been setup. This is used in SCSI because we
* have to have a setup device to begin using the HBA, but after we
* send the initial inquiry, we use configure to extract the device
* parameters. The device need not have been added to be configured.
*/
void transport_configure_device(struct device *dev)
{
attribute_container_device_trigger(dev, transport_configure);
}
EXPORT_SYMBOL_GPL(transport_configure_device);
static int transport_remove_classdev(struct attribute_container *cont,
struct device *dev,
struct device *classdev)
{
struct transport_container *tcont =
attribute_container_to_transport_container(cont);
struct transport_class *tclass = class_to_transport_class(cont->class);
if (tclass->remove)
tclass->remove(tcont, dev, classdev);
if (tclass->remove != anon_transport_dummy_function) {
if (tcont->statistics)
sysfs_remove_group(&classdev->kobj, tcont->statistics);
attribute_container_class_device_del(classdev);
}
return 0;
}
/**
* transport_remove_device - remove the visibility of a device
*
* @dev: generic device to remove
*
* This call removes the visibility of the device (to the user from
* sysfs), but does not destroy it. To eliminate a device entirely
* you must also call transport_destroy_device. If you don't need to
* do remove and destroy as separate operations, use
* transport_unregister_device() (see transport_class.h) which will
* perform both calls for you.
*/
void transport_remove_device(struct device *dev)
{
attribute_container_device_trigger(dev, transport_remove_classdev);
}
EXPORT_SYMBOL_GPL(transport_remove_device);
static void transport_destroy_classdev(struct attribute_container *cont,
struct device *dev,
struct device *classdev)
{
struct transport_class *tclass = class_to_transport_class(cont->class);
if (tclass->remove != anon_transport_dummy_function)
put_device(classdev);
}
/**
* transport_destroy_device - destroy a removed device
*
* @dev: device to eliminate from the transport class.
*
* This call triggers the elimination of storage associated with the
* transport classdev. Note: all it really does is relinquish a
* reference to the classdev. The memory will not be freed until the
* last reference goes to zero. Note also that the classdev retains a
* reference count on dev, so dev too will remain for as long as the
* transport class device remains around.
*/
void transport_destroy_device(struct device *dev)
{
attribute_container_remove_device(dev, transport_destroy_classdev);
}
EXPORT_SYMBOL_GPL(transport_destroy_device);
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